Condensation polymerisation

Need to know

What you need to know

• Polyamides contain the repeating amide linkage: $-CONH-$.
• They are formed from monomers containing amine ($-NH_2$) and carboxylic acid ($-COOH$) groups.
• The polymer chains are held together by strong intermolecular hydrogen bonds between the polar $C=O$ and $N-H$ groups.
• This extensive hydrogen bonding gives polyamides high melting points and high tensile strength, making them suitable for fibres and ropes.

Explanation

Building Chains, Losing Molecules

1. A small molecule, such as water (H₂O) or hydrogen chloride (HCl), is eliminated every time two monomers join.
2. Polyesters form when a dicarboxylic acid and a diol monomer react, creating a repeating ester linkage (–COO–).
3. Polyamides form from a diamine and a dicarboxylic acid (like Nylon), or from self-reacting amino acids (like proteins), creating a repeating amide linkage (–CONH–).
4. To draw the polymer, identify the repeating unit formed after the small molecule is removed, and place it in square brackets with continuation bonds.